What can i do about reclaiming my property?

Me and my girlfriend have lived together for 2 years, we recently have been having very bitter arguments which has resulted in me leaving her, at the start I had moved in all of my things, which I have managed to move out of her place but some things that I have bought in the time we have been together with my money she refuses to give back, claiming that there hers, which at the begging I stated they were jointly mine and hers but overall mine because I bought them, one of which is a Nikon D5000 camera which cost me £500 when I bought it, she uses it a lot more than I do for her home run business but because I never use it and she see's it as a gift from me to her, that she will not let me take it if I move out and even threatening to sell the things I can't manage to take with me all in one go, I'm very scared as these things cost me quite a lot of money and I have no receipts or any evidence apart from a bank statement in my name from Argos for £500 which could be anything as it hasn't got what was sold on the bank statement!

Can I get the Police involved?

This is a tricky situation and would be much easier with receipts but as you don't have them it would certainly be best to get some legal advise not sure at this stage the police are the first option unless you feel there will be an altercation when you collect your belongings in that case it might be in your best interest to have police present in regards to your bank statement that can still act as proof of purchase Did argos take any details from you at the time of purchase? Have you got any insurance on the camera in your name? These may help you also

As for the camera your bank statement shows a date and a purchase amount.
The store may have further info in a customer file which some stores maintain.

Talking with the police could clarify what you can or must do to retrieve your
stuff. Have a list of the items in question so that you can be as specific as
possible. She's admitting the remaining stuff is yours if she plans to throw it
out rather than let you retrieve it.

It could expedite the return of your other items if you decide to let her keep
the camera. You know the situation better than anyone else, but I think
police input is crucial to your cause.